Problem: Takahashi loves sorting.

He has a permutation (p_1,p_2,...,p_N) of the integers from 1 through N. Now, he will repeat the following operation until the permutation becomes (1,2,...,N):

* First, we will define high and low elements in the permutation, as follows. The i-th element in the permutation is high if the maximum element between the 1-st and i-th elements, inclusive, is the i-th element itself, and otherwise the i-th element is low.
* Then, let a_1,a_2,...,a_k be the values of the high elements, and b_1,b_2,...,b_{N-k} be the values of the low elements in the current permutation, in the order they appear in it.
* Lastly, rearrange the permutation into (b_1,b_2,...,b_{N-k},a_1,a_2,...,a_k).



How many operations are necessary until the permutation is sorted?

Constraints

* 1 ≤ N ≤ 2×10^5
* (p_1,p_2,...,p_N) is a permutation of the integers from 1 through N.

Input

Input is given from Standard Input in the following format:


N
p_1 p_2 ... p_N


Output

Print the number of operations that are necessary until the permutation is sorted.

Examples

Input

5
3 5 1 2 4


Output

3


Input

5
5 4 3 2 1


Output

4


Input

10
2 10 5 7 3 6 4 9 8 1


Output

6

Solution (in CPP):

Solution:
//by xiqiao
#include<bits/stdc++.h>
#define maxn 200005
using namespace std;
typedef long long ll;
int q[maxn],t[maxn],f[maxn];
int n;
bool check(int x,int y,int z){
	if(x<y && y<z)return 1;
	if(y<z && z<x)return 1;
	if(z<x && x<y)return 1;
	return 0;
}
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		int x;scanf("%d",&x);q[x]=i;
	}
	for(int i=n-1;i;i--){
		if(t[i+1]==0){
			if(q[i]>q[i+1]){
				t[i]=1;f[i]=i+1;
			}
		}
		else if(check(q[f[i+1]],q[i],q[i+1])){
			t[i]=t[i+1];f[i]=f[i+1];
		}
		else {
			t[i]=t[i+1]+1;f[i]=i+1;
		}
	}
	printf("%d\n",t[1]);
	return 0;
}